The present invention relates to a system for making roofs or coverings for buildings, particularly (but not exclusively) for buildings for industrial use, such as sheds and the like.
Industrial sheds are frequently covered with coverings known as the xe2x80x9cshedxe2x80x9d type, consisting of a plurality of pre-stressed concrete beams between which are disposed flat or curved covering panels, one edge of each of which rests on one of the beams, while the other rests on struts of a glazed unit which provides illumination for the premises. In some cases, the glazed units are provided with apertures to provide ventilation for the premises.
In hot climates, the problem arises of ventilating premises which are intensively heated by the sun which irradiates the covering. The panels and the beams forming shed coverings are raised to high temperatures as a result of the irradiation, and this heat is transmitted into the interior of the premises. The glazed unit apertures may in some cases cause air at a higher temperature than the internal temperature to enter the building, thus preventing the outflow of the hot air from the interior and actually causing further heating. This occurs, for example, in the case of wind blowing toward the glazed units: it is possible for air currents to be generated and to flow over the external surface of the covering, with a consequent heating of the air which, when heated in this way, penetrates to the interior of the premises through the apertures of the shed covering.
Covering panels provided with layers of insulating material do not enable sufficient thermal insulation to be obtained, especially in torrid and tropical climates, simply because of the impossibility of extracting the hot air from the interior of the premises in an efficient way.
The object of the present invention is to provide a covering system which avoids the disadvantages of conventional coverings.
More particularly, a first object of the present invention is to provide a covering system which provides efficient ventilation of the premises beneath it, by preventing the ingress of hot external air and permitting the outflow of hot air from the interior.
The object of one particular possible embodiment of the invention is the provision of a covering system which provides a powerful ventilation of the premises beneath it in periods of high ambient temperature, and prevents the dissipation of heat in the colder periods.
These and additional objects and advantages, which the following text will make evident to those skilled in the art, are achieved with a system comprising at least one panel capable of being placed on said covering in an inclined position with respect to the horizontal, this panel having an inner chamber, a plurality of suction apertures through which the inner chamber communicates with a void inside the building, and a discharge aperture disposed in the vicinity of the area of the panel which is at a higher level when the panel is installed.
When installed, the panel is disposed with its suction apertures toward the interior of the building and with its discharge aperture disposed toward the exterior. In this way a path is created for an air current which develops through the suction apertures, the inner chamber of the panel and the discharge aperture. In this path, a suction effect is generated by the heat, causing hot air to be extracted from the layers closest to the covering, with consequent expulsion of the hot air to the exterior and suction of lower-temperature air through windows, doors or apertures made in the most suitable points of the building, preferably in the lower area. The suction effect is produced simply by the heating of the internally hollow panel which, with the suction and discharge apertures, forms a kind of chimney. The presence of an inner chamber in the panel also reduces the temperature of the surface of the panel facing the interior of the covered environment, reducing the effect of heating by radiation. The surface area of the air chamber may be identical to that of the panel, or may correspond to only a part of it.
Theoretically, the discharge aperture may be made in any shape, the only significant characteristic being its location in an area at a sufficiently high level with respect to the suction apertures. Preferably, however, the discharge aperture is made in the shape of a slot which extends in the direction of the width of the panel, in the vicinity of the upper edge of the panel and preferably over the whole width, in such a way as to generate an outgoing air current which is uniform over the whole transverse extension of the panel.
The discharge aperture may be delimited by the two parallel edges of two sheets delimiting the lower and upper surfaces of the panel. In this case, the lower sheet is larger than the upper sheet, thus leaving an aperture on the upper surface of the panel, from which the hot air can flow out. According to a particularly advantageous embodiment, however, the slot which forms the discharge aperture is delimited by sections which are inclined with respect to the panel. The inclination of the sections is such as to prevent any wind which may strike the sides of the building from impeding the outflow of hot air from the interior through the slot. The presence of the sections also increases the suction effect due to the temperature, in other words what is known as the xe2x80x9cchimneyxe2x80x9d effect.
To prevent the penetration of rain water through the discharge aperture and the suction apertures into the building, it is possible for the suction apertures to be absent in the area corresponding to the discharge aperture. It is also possible to provide suitable means which prevent the penetration of the water, for example projections or protective edges above or around the suction apertures.
The panel may theoretically be made from any material. According to a preferred embodiment, it is made from sheet metal, for example aluminum sheet (to avoid problems of corrosion and to obtain a particularly light structure). In this case, the panel may be formed from an upper sheet and a lower sheet connected together by connecting means, for example lattice beams, connecting brackets, internal diaphragms, grids, internal or external bars, or other equivalent systems. The two sheets and said connecting systems can thus form a panel which can be self-supporting and is very light.
According to a particularly advantageous embodiment, at least the upper panel has a troughed cross section with channels and ribs extending longitudinally with respect to the said panel. The lower panel may be flat or may also have a corresponding fretted cross section. Depending on the shape of the lower panel, various systems may be provided to collect and discharge any rain water which may penetrate through the discharge aperture or slot. For example, if the lower panel is shaped with a troughed cross section, the longitudinal channels present in it may act as water drainage channels and in this case one or more water discharge slots are provided on the back. Conversely, particularly if the lower sheet is flat, a front transverse channel, extending parallel to the discharge slot or aperture, may be provided for the collection of the rain water.
Alternatively, an external protective section may be provided above the discharge slot.
When it is wished to have a covering panel which is also usable in climates in which the ambient temperature may fall to levels such that ventilation and the extraction of hot air from the interior of the building are no longer necessary, the covering panel may advantageously be provided with means of intercepting or closing the suction apertures or the discharge aperture. These closing means may be made in the form of one or more sliding diaphragms having apertures corresponding to the suction apertures and capable of assuming, alternatively, a position in which the apertures of the diaphragm coincide with the suction apertures or one in which they are out of alignment with them. In the first case, the air can flow through the panel, while in the second case the flow of extracted air cannot be established and consequently the heat is not extracted from the environments beneath. Alternatively, a shutter may be provided to close the discharge aperture, or a closing partition may be provided inside the chamber to intercept the path of the air between the discharge aperture and the suction apertures.
The covering system according to the invention can also be advantageously applied to buildings for non-industrial use and also, in particular, to buildings with multiple floors or levels. In this case, at least one of said panels which is in communication with the void beneath it (the loft, for example) is disposed on the covering of said building.
The present invention differs from the conventional ventilation systems of coverings for non-industrial buildings, in which gaps are provided between the roof and an underlying insulating layer: in these conventional solutions the only ventilation is by means of air sucked from the exterior, which generates a current flowing over the insulation under the roof tiles. However, there is no extraction of hot air from the interior of the building.
Further advantageous embodiments of the invention are described below and are indicated in the attached claims.